Radio frequency transducer



Mai-ch 4, 1958 M. ARDITI RADIO FREQUENCY TRANSDUCER 2 Sheeos--Sheei'l 1 Filed July 22, 1953 MAV4 @AWG

v INVENTOR MAUR/Cf RD/T/ 'BY /O M .March 4, 19,58

M. ARDITI RADIO FREQUENCY TRANSDUCER K 2 Sheets-Sheet 2 Filed July 22, 1953 @ffy/0 United States Patent @ffice 2,825,875 Patented Mar. 4, 1958 RADI() FREQUENCY TRANSDUCER Maurice Arditi, Clifton, N. J., assignor to International Telephone and Telegraph Corporation, a corporation of Maryland Application July zz, 1953, serial No. 369,643

16 claims. (c1. ssa-s4) This invention relates to radio frequency transducers and more particularly to transition structures from co-A axial waveguides to single or parallel conductor waveguides.v

Attempts have been made heretofore to provide transition couplings between coaxial waveguides and single or parallel conductor waveguides but such prior transition structures have either involved special expensive plumbing'or elaborate and relatively expensive horn structures. It is an object of the present invention to provide a transducer for use between coaxial waveguides and single or parallel conductor waveguides which is relatively simple and inexpensive to build.

Briefly, the transducer according to the principles of the present invention comprises two conductors, one of elongated form and the other of a wider conguration such as to present a planar conducting surface facing the first mentioned conductor. The two conductors are preferably spaced apart by a layer of dielectric material to maintain them in substantially parallel relation. Energy propagated over a coaxial waveguide is transferred to the parallel conductor arrangement by providing an opening through the planar conductor, the outer conductor of the coaxial waveguide being connected to the planar conductor coaxially of the opening with the inner conductor extending through the opening in electrical connection with the first or elongated conductor. Radio frequency energy propagated along the coaxial line is transferred readily for propagation along the first and second conductors in substantially the same mode of propagation as in the coaxial line. The wave energy is transferred from the spaced conductors to a waveguide of either the single conductor type or the parallel conductor type. Where itl is to be transferred to a single conductor the planar conductor is slotted along the zone underlying the elongated conductor, the slot being tiaredV gradually away from the elongated conductor whereby the wave energy is satisfactorily launched for propagation along an extension of the single elongated conductor. For propagation along a waveguide of parallel conductors, a third conductor is disposed in parallel relation to the elongated conductor or an extension thereof and is either coupled directly to the planar conductor or is disposed in parallel relation thereto. In the latter case, the planar conductor is terminated preferably in a tapered form a short distance from thecoaxial coupling.. g

The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent by reference to the following dej scription taken in conjunction with the accompanying drawings, wherein:

Fig. 1 is a view in perspective with parts cutaway to show one embodiment of the invention wherein a coaxial line is coupled to a waveguide of parallel conductors;

Fig. 2 is a view in cross-section taken along line 2-2 of Fig. l;

' Fig. 3 Ais a view in cross-section similar to Fig.` 2, showing the parallel conductors with a greater spacing;

Fig. 4 is a View in perspective of another embodiment of the invention wherein the conductors of the transducer are coupled to a waveguide of parallel conductor supported on a strip of dielectric material;

Figs. 5 and 6 are cross-sectional views taken along lines 5-5 and 6 6, respectively, of Fig. 4;

Fig. 7 is a view in plan of a modified form of coupling arrangement between a waveguide of parallel conductors and the conductors of the transducer;

Fig. 8 is a view in side elevation with parts broken away showing a modified form of the coupling arrangement illustrated in Figs. 4 and 7;

Fig. 9 is a view in cross-section taken along line 9-9 of Fig. 8;

Fig. 10 is a cross-sectional view similar to Fig. 9 showing a slight variation of the parallel conductor waveguide that may be employed; and

Fig. 1l is a view in plan of a further embodiment of the invention showing a transducer arrangement coupling a coaxial line to a single conductor waveguide,

Referring to Figs. 1 and 2 of the drawing, the transducer of the'p'resent invention is shown to comprise a rst conductor 1 of elongated form and a second conductor 2 of planar form spaced apart by a layer of dielectric material 3. The planar conductor 2 as well as the layer of dielectric material is made wider than the conductor 1 so that radio frequency wavesmay be propagated therealong in a mode having some properties of the TEM mode. Wave energy from a coaxial waveguide is coupled to this type of parallel waveguide by providing the planar conductor 2 with an opening 4 about which is coupled the outer conductor 5 of a coaxial waveguide 6. The inner condluctor 7 is extended through the opening 4 and is connected directly to the elongated conductor 1 as indicated at 8. The transducer may have coupled thereto as an extension thereof a waveguide of paraHel condoctors as indicated by conductors 1a and 2a and dielectrie layer 3a. The conductor 2a is disposed in parallel relation to the conductor 1a on the same side of the dielectric layer 3a. These conductors may be formed by known printed circuit technique, additional information on which may be obtained by reference to the copending application `of M. Arditi-P. Parzen, Serial No. 286,764, led May 8, 1952, now U. S. ,Patent No. 2,774,046. The conductor 2a is preferably extended in overlying parallel relation to the planar conductor 2, the conductor 2a being angled away from conductor 1 as indicated at 9 and terminated by a layer of attenuating material 10 disposed thereon. The planar characteristic of conductor 2 is pref- .verably terminated a short distance from the coupling opening 4, the termination preferably being in a taper as indicated at 2c.

While the propagation of wave energy from the coaitial waveguide 6 to the transducer conductors 1, 2 is performed readily in similar modes, the transfer of the wave energy from the conductors 1, 2, to conductors 1a, 2a, undergoes an angular translation through 90. It will be understood from the view of Fig. l that the electric field is substantially normal to the conductors 1 and 2 and in the angular translation must shift so as to be normal to the edge portions of the two conductors 1a, 2a. The electromagnetic tield thus assumes a mode of propagation characteristic of parallel lines completely immersed in dielectric even though the two conductors are supported on the same side of a strip of dielectric material, it being understood, of course, that there will be some variation inthe eld distribution in view of the difference between the dielectric coeicient of the dielectric material and open space.

this-spacingmay=-bevaried*toV a much larger spacing d2 i being employed for the tests:

Spacing (d) Attenuation .imdb/meter'.

1 rnrn 3. 510.2 2.5 mm- 28:1;0. l. 9 mm 'l'.ill ll` In Figs. 4, 5.and6 .the transducerarrangement is :shown wherein the.. angular. translation of. the `electric: Yel'dv is avoided. The transducer is shown to include a f'rst .conductor 11 of elongated tapered .form and a Vsecon'd'conductor 12 of. planar -configuration separated by a 'layer of. dielectric material 13. The. two conductors 11'and`I2 are Yboth tapered toward the point of coupling to a parallel conductorwaveguide, itfbeing preferable to'tape'r the.

two conductors to the dimension corresponding to that of the line conductors. This taper of conductor 12'termi`- nat'es the planar characteristic thereon the plane of the conductor 1'2lat its connection to one of the conductors of the parallel conductor waveguide. The dielectric `layer may likewise betapered although it`could'be left'un'- tapered, ifl desired. As shown in Fig. 4 the parallel line",

conductors comprise two strip conductors 14 and 15 car; ried on one side'` of a strip of dielectricmateral 16. The dielectric material 1'6 is disposed at right'ang'les to'the layer' 13 and 'thejspacing of the conductors 14 and'15' in' this illustration is shown to be the same as 'the Vthickness of Vthe layer 13. The conductors 14 vand 15 are tapered as indicated at 14a .and 15a so that the widths thereof correspond to the Vthickness of the conductors 11 and '12.

It'Willbe readily apparent from Fig. 4 that the wavev energy is practically undisturbed in its `propagation from conductors 11, 12 to'conductors 14, 15, thetapered p0rtions of the `four conductors beingigradual throughout with the transition.' 'Byl providing'a second transducer` in serieswith conductors' 1'4 'and' 15 the'conductor -14-may be coupled*to`thesecond"'or"ground 'conductorand conductor 15to the-tirstor line conductor, thus effecting poe` lan'ty inversion.

In Fig.v 7 the tapered portions 1417 'and'15b"ofstrip conductors14 andl 1S areV shown -to loverlapl conductorsV v11-'and 1'2. In ythis form the -Wave 'propagation' is alsopractically undisturbed Lsincetlie'spacing between theconf ductors/11, 12 and Vconductors 14, I5 may `be maintained substantially uniform :while the I`two tapered portions are disposed in overlapping relation thus providingfory a' stronger joint than that shownrin Fig-4.

In Fig. l8 a coupling similar tothat shown .in Fig. 7

sillustrated wherein the conductors 17, 1 8 of the parallel conductor'waveguide are embedded -in a .layer` of-.dielectricmaterial 19 and wherein Vthespacing between such conductorsvis greater than thespacing between .thercon-v ductors 11, 12. The tapered Vportions lband'l'zbxare wedged `outwardly fromV thedielectric `layer 13 by means:Y

of: dielectric wedges 20 :and` 21. vThese Wedgesprovide asupport for the thin layers vrof conductive material -forrn'-A ing the conductors 11b, 12b. While thevconductors17 andlS may be embedded in dielectric material as .shown in Figs; 8 and. 9, Vsome vimprovement .is .obtained by exposing the .two conductors Aas indicated inFig. at 17a' and 18a.

For a 300 ohm television .lead-in line'with` a *n spacing between centers of conductors V17 Van`cl"18`\off8 mm., a thickness of dielectric 19at 1:5 mm., and an operating frequency of 4700 nic/sec. the attenuation'was 1.1' t0.'1 'db/meter for-thetom shown in Fig. '9i-fand .lation to said planar surface.

0.9:1- 01 db/meter for the form shown in Fig. 10. The wedge. spread at 20, Fig.-8, and the taperofconductor.. 11, Fig. 4, also provide for coupling high impedance parallel conductor waveguides to relatively low impedance transducer arrangements, for example 300 ohms to ohms.

The transducer shownY in Fig..v 11 provides for translation of wave energy propagated along a coaxial waveguide to a'single conductor waveguide.: Theltransducer structure is similar to the structures hereinabove. de.- scribed except that the Velongated.:conductor 211 mayj-"bev continued beyond the transducer as the singleconduetor waveguide 21a. The conductor 21 is spaced from the planar conductor 22 'by a layer of-dielectric lmaterial 23. The planar conductor 22,.however, isprovided with a slot 24 a short distance from the coaxial coupling indicated at 25, the slot being disposed in underlying relation to the elongated conductor 21. The edges of the planar conductor 22 Ydefini-ng tthe :slot-are lil'aredzoutwardly-:fromitle conductor 2:1.:as1indicatedfat 26 and27xtherebyi providing.; a Atranslation .oi` themode .of ipropagation. .between ,theiconductors 21, 23 to a mode of propagation alongj..tlte;y single conductor 21a.v Theiirsingle;.'conductor.21a;;mayf.be supported .byl aLstrip of: dielectric-1as7 indicated at 23a:- or it smay -be .supported inropenair', .whichever fisfdesired; Suchzsingle lineaconductors operate-satisfactorily as-.waveguides provided .the resistivity .thereof is ofgaproper value; To insure proper resistivity;-.otwthe line it iisasome `itimes 1 desirable to .coat `the line :with a .dielectric material, such as enamel;

While I have described above the-pprinciples-of. myinf. vention in connection `with:specific-.apparattlmit .isftobe clearly understoodthat thisz=descrption is .made by -way of `example onlyvand not as aflimitationfto 'the scopeof my 'invention .as -setforth in. thenobjects thereoilandl fin.Y theaccompanyingiclaims.

.VI claim: v j

1. Atransducer forradiofrequency energy comprising` a.;rst vconductor -of elongated .form,.a secondv conductor. disposed in dielectrically spaced substantiallyparallel:relation .to said rst conductor, said, secondconductorbeing wider. than said lfirst conductor .to presentajplanar surface in a given tplanenfacing,.-said,iirstA conductor, said second conductor having VanV opening. therethrough, a.. lco-m axial waveguidedisposed with the outer conductor thereofin electricalfconnection with said. second conductor about.: said. openinggandv .the inrlergconduetorv thereof.extended;V through said-opening-,ginfelectrical .connection `withtsadQ` rst conductonvtsaidtirst conductor. being'extendedfromY saidgopening V,for propagation `of radio rfrequency, waves.. therealong saidv secondeonductor. hav ing.,atv least..tl:t`eV planar characteristic thereof. in Vsaid;given.plane .terminated a sl1 ;rt-..distance` y,frfonrsaid opening. ;by a vtapered portion. with.. the, :taper `in the :directionfoflthe extension of. fsaidY :rst .conductor whereby radio. :frequency waves' propagated along.A said coaxial .waveguide is. transferred for propagation alongsaid iirstconductor.

2.'. A transducer. according. to. .claim y1, wherein .said i first conductor has .associateditherewlith .a. third conductor.` ofelongatedormdisposed in parallel relationthereto and constituting :therewithta waveguide oflparallel conductors,y said third conductor .being also disposed Afora portion ofv its length 4in dielectrically.spacedsubstantally` parallel re- 3. A. transducer according .to claim '2; wherein said third :conductorhas: .associated .with said portion thereof.. a` layer of .attenuating ,material thereby` terminating the conducting,characteristic voffsaid third conductor.

4. A transducer according to claim 1.,' wherein safid. second conductor has-.its .said terminated planar: charac=v teristic...with-..an.:elongated Vsl'ot idi'sposedinv substantially parallelunderlying relation to ysaidifst conductor withtlier sides fof V:saidslot .flaring `outwardly from .-,said'irstco`n ductor. p

5. .A transducer .toi-radio :frequency .energy .comprising aaaaave arst conductor 'of elongated form, a second conductor, va layer of dielectric material interposed between said first .and second conductors to maintain them in spaced substantially parallel relation, said second conductor being wider than said first conductor to present a planar surface in a given plane facing said first conductor, said second conductor and said layer of dielectric material having openings .extending therethrough in alignment with said first conductor, a coaxial waveguide disposed with the outer conductor thereof in electrical connection with said second conductor coaxially of said openings and the inner conductor thereof extended through said openings in electrical connection with said first conductor, said first vconductor being extended from said opening for propagation of radio frequency waves therealong said second conductor having at least the planar characteristic thereof in said given plane terminated a short distance from said openings by a tapered portion with thetaper in the direction of the extension of said first conductor whereby radio frequency waves propagated along said coaxial waveguide is transferred for propagation along said first conductor.

6. A transducer according to claim 5, wherein said rst conductor has associated therewith a third conductor portion of elongated form disposed in parallel relation thereto and on the same side of said layer of dielectric material as said first conductor.

7. A transducer according to claim 5, wherein said second conductor has its said terminated planar characterisic thereof shaped to include an elongated slot disposed in substantially parallel underlying relation to said first conductor with the sides of said slot fiared outwardly away from said first conductor.

8. A transducer according to claim 5, wherein said `first and second conductors have joined contiguously thereto a waveguide of parallel conductors at a point of minimum width, the parallel conductors of said waveguide being maintained in parallel relation by a layer of dielectric material disposed at right angles to the plane of the layer of dielectric material interposed between said first and second conductors whereby the electric field propagation in a mode approximating the TEM mode along said first and second conductors is transferred for propagation along said parallel conductors in said TEM mode.

9. A transducer according to claim 8, wherein said parallel conductors are spaced apart a greater distance than the spacing between said first and second conductors, and dielectric wedge portions disposed on opposite sides of said first mentioned layer of dielectric material to support connecting lengths of conductors between the parallel conductors and said first and second conductors, respectively.

10. A transducer according to claim 8, wherein said waveguide of parallel conductors comprises two conductors in strip form carried by a layer of dielectric material, the width of said strip conductors being tapered with the tapered portions thereof disposed in overlapping relation to at least part of said first and second conductors.

ll. A transducer for radio frequency energy comprising a first conductor of elongated form, a second conductor, a layer of dielectric material interposed between said first and second conductors to maintain them in spaced substantially parallel relation, said second conductor being wider than said first conductor to present ;a planar surface in a given plane facing said first conductor, said second conductor and said layer of dielectric v1 material having openings extending therethrough in alignment with said first conductor, a coaxial waveguide disposed with the outer conductor thereof in electrical connection with said second conductor coaxially of said openings and the inner conductor thereof extended through said openings in electrical connection with said first conwaveguide being maintained in parallel relation by a` layer of dielectric material disposed at right angles to the plane of the layer of dielectric material interposed between said lirst and second conductors, said first and second conductors being tapered to the parts thereof which are connected to said parallel conductors, the taper being such as to make the width of the lirst and second conductors correspond respectively to the thickness of said parallel conductors.

12. A transducer for radio frequency energy comprising a first conductor of elongated form, a second conductor, a layer of dielectric material interposed between said first and second conductors tol maintain them in spaced parallel relation, said second conductor being wider than said first conductor to present a planar conductive surface in a given plane facing said first conductor, said second conductor having at least the planar characteristic thereof in said given plane terminated by a tapered portion with the taper in the direction of the extension of said first conductor, a waveguide of parallel conductors joined contiguously to said first and second conductors at a point of minimum width, the parallel conductors of said waveguides being maintained 1n parallel relation by a layer of dielectric material disposed at right angles to the plane of the layer of the dielectric material interposed between said first and second conductors, whereby the electric field propagation in a mode approximating the TEM mode along said first and second conductors is transferred for propagation along said parallel conductors in said TEM mode.

13. A transducer according to claim l2, wherein said parallel conductors are spaced apart a greater distance than the spacing between said first and second conductors, and dielectric wedge portions disposed on opposite sides of said first mentioned layer of dielectric material to support connecting lengths of conductors between the parallel conductors and said first and second conductors, respectively.

14. A transducer according to claim l2, wherein said waveguide of parallel conductors comprises two conductors in strip form carried by a layer of dielectric material, the width of said strip conductors being tapered with the tapered portions thereof disposed in overlapping relation to at least part of said first and second conductors.

15. A transducer for radio frequency energy comprising a first conductor of elongated form, a second conductor disposed in dielectrically spaced substantially parallel relation to said first conductor, said second conductor being wider than said first conductor to present a planar surface in a given plane facing said first conductor, said second conductor having an opening therethrough, a coaxial waveguide disposed with the outer conductor thereof in electrical connection with said second conductor about said opening and the inner conductor thereof extended through said opening in electrical connection with said first conductor, said first conductor being extended from said opening for propagation of radio frequency waves therealong, said second conductor having at least the planar characteristic thereof in said given plane terminated a short distance from said opening by a tapered portion with the taper in the direction of the extension of said first conductor whereby radio frequency waves propagated along said coaxial waveguide are transferred for propagation along said first conductor, and said first conductor has associated therewith a third conductor portion of elongated form disposed in parallel relation thereto to constitute a waveguide of parallel conductors, said third conductor constituting a continuation of said second conductor beyond the termination of said planar characteristic. in saidgivenk p1ane,. whereby the electric.

TEMrmode:

-165 transducer for'radiofrequencyenergy compris; in garst'conductor of eiongatedrform; asecond'conduc'- tor, a'iayerof 'dielectri materia]V interposed' betweensaidv 'st and-second-l conduct'ors "to maintain them -in'V spaced" paralll'relation, saidk second' conductorbengwider thanY said v'rst' conductor to yresent 'a' planar` conductive surface-'in a Agiven plane facing saidrst conductor, said' sec# ond;fconductori'having" at least the pianar characteristic' thereof iin' said" given' plane terminated: by a" tapered E p'ortionf'witn'the tapery in the direction off the extension of;VV said rst conductor, a waveguide of. parallel' conductorsl coup'ied'to Asaid' first0 andisecond' conductors; the parallel conductors of saidA waveguides-being mantainedfin'paraile'irelationby a 'layerof-A 'dielectrcmaterial disposed at rightanglesto the plane'of thef'iayerof the diellectricma'- f teral interposed between said rst and second conductors,

conductors.

25,602,355 kunnen f July-8,1952 2,7 34L-l17v0i Engelman e. 

